This invention is directed to novel halogenated paclitaxel analogs and derivatives, processes for their preparation and use as effective anti-tumor agents.
Several important compounds from the taxane family of terpenes have been identified as possessing strong anti-neoplastic activity against various cancers. For example, paclitaxel (1), having the following structure, 
has been approved by the Food and Drug Administration for the treatment of ovarian cancer and breast cancer, and is presently undergoing clinical trials for treatment of various other cancers, including lung and colon cancer.
Cephalomannine has been reported to be effective in causing remission of leukemic tumors (see U.S. Pat. No. 4,206,221) and is most often present with its structurally similar analog, paclitaxel. The structure of cephalomannine (2) is shown below: 
Paclitaxel and cephalomannine are only some of the many natural products from the taxane family which can be found, for example, in the bark of the Pacific yew tree Taxus brevifolia and other yew species such as T. baccata, T. cuspidata, as well as T. yunnanensis and other plant materials including T. hicksii, T. densiformis, T. gem. T wardii, T. capitata, T. brownii, and T. dark green spreader. These compounds can also be found in Cephalotaxus species, such as, for example, Cephalotaxus manni as well as cultured plant cells and fungi.
The supply of paclitaxel, cephalomannine and other important taxanes is, however, limited to a finite amount of yew trees and other vegetation in which they are present in small amounts. Thus, alternative compounds having paclitaxel-like or cephalomannine-like anti-tumor activity are highly desirable to increase the armamentarium of clinical therapeutic agents.
In the U.S. application Ser. No. 08/654,424, filed May 29, 1996, and U.S. application Ser. No. 08/672,397, filed May 29, 1996, now U.S. Pat. Nos. 5,807,888 and 5,824,278 respectively, the entirety of each being incorporated by reference herein, the synthesis, separation and anticancer activity of several dihalocephalomannine diastereomers is provided. In this study, two diastereomeric 2xe2x80x3, 3xe2x80x3-dibromocephalomannines and their two corresponding 7-epimers were obtained by treatment of extracts of Taxus yunnanensis with bromine solution, under mild conditions. Treatment of the same extract with chlorine solution yielded four diastereomeric 2xe2x80x3, 3xe2x80x3-chlorocephalomannines. The diastereomeric mixtures were separated into the individual components by preparative HPLC on C18 reversed-phase silica gel. A more efficient analytical separation seas obtained on a penta-fluorophenyl bonded phase. The compounds were isolated and fully identified by classic and modem methods. Slight differences were observed in the NMR spectra of the 7-epimers when compared to their 7xcex2-OH analogs. On the basis of a comparison of physico-chemical data, the bromo compounds were identified as (2xe2x80x3R,3xe2x80x3S)-dibromo-7-epi-cephalomannine (3), (2xe2x80x3S,3xe2x80x3R)-dibromo-7-epi-cephalomannine (4), (2xe2x80x3R,3xe2x80x3S)-dibromo-cephalomannine (5), (2xe2x80x3S,3xe2x80x3R)-dibromocephalomannine (6). The chloro compounds were identifed as (2xe2x80x3R,3xe2x80x3R)-dichlorocephalomannine (7), (2xe2x80x3S,3xe2x80x3S)-dichlorocephalomannine (8), (2xe2x80x3R,3xe2x80x3S)-dichlorocephalomannine (9), and , (2xe2x80x3S,3xe2x80x3R)-dichlorocephalomannine (10).
Cytotoxic activity was tested against the NCI 60 human tumor cell line panel in comparison with paclitaxel and results were obtained showing strong antineoplastic activity against several tumor lines, including, but not limited to, leukemia cell line HL-60 (TB); Non-Small Cell Lung Cancer Line NCI-H522; Colon Cancer Cell Lines COO 205 and HT29, CNS Cancer Cell Lines SF-539 and SNB-75; Ovarian Cancer Cell Line OVCAR-3; Renal Cancer Cell Line RXF-393; and Breast Cancer Cell Lines MCF7, MDA-MB-231/ATCC, HS 578, MDA-MB-435 and MDA-N.
The structures of some of these dihalogenated cephalomannines are set forth below:
In accordance with the present invention, there are now provided several novel halogenated derivatives of paclitaxel and cephalomannine for use as anticancer agents, which have structures selected from the next two general formulas A and B: 
For General Formula A:
wherein R1 is mono or dihalogenated acyl group, aroyl group (Table 1), alkyloxy-carbonyl group or aryloxy-carbonyl group (Table 2) and R3 is hydrogen or halogenated group, and R2 is hydrogen or acetyl groups;
wherein R4 is PhCO or Me3COCO or CH3CHxe2x95x90C(CH3)CO, R3 is a halogenated group (Tables 1 and 2);
For general formula B:
wherein R1 is mono or dihalogenated acyl group or aroyl group (Table 1), alkyloxy-carbonyl group or aryloxy-carbonyl group (Table 2) and R2 is hydrogen or acetyl group, and R5 is any group from Table 3;
R6 is H or Me; 
wherein
R1 is a group selected from Table 1 (groups 1 to 40);
and R2 is H or Ac;

wherein
R1 is a group selected from Table 2 (groups 41 to 95);
R2 is H or Ac; 
wherein
R3 is a group selected from Table 1 (groups 1 to 40);
and R2 is H or Ac, and R4 is PhCO or Me3COCO or CH3CHxe2x95x90C(CH3)CO; 
wherein
R3 is a group selected from Table 2, (groups 41 to 95),
R2 is Ac or H, and R4 is PhCO or Me3COCO or CH3CHxe2x95x90C(CH3)CO; 
wherein
R1 is a group selected from Table 1 (groups 1 to 40);
R2 is H or Ac;
R3 is a group selected from Table 2 (groups 41 to 95); 
wherein
R1 is a group selected from Table 2 (groups 41 to 95);
R2 is H or Ac;
R3 is a group selected from Table 1 (groups 1 to 40); 
wherein
R1 is a group selected from Table 1 (groups 1 to 40);
R2 is H or Ac;
R3 is a group selected from Table 1 (groups 1 to 40); 
wherein
R1 is a group from Table 2 (groups 41 to 95);
R2 is H or Ac;
R3 is a group selected from Table 2 (groups 41 to 95); 
wherein
R1 is a group selected from Table 1 (groups 1 to 40);
R2 is H or Ac;
R5 is H or Me or Ac or Ph or Bz or G1 or G2 or G3 or G4 or G5 or G6 or G7 or G8 or G9 G10 or G11 or G12 or G13;
R6 is H, only in the case when R5 is G10 the group R6 is H or Me; 
wherein
R1 is a group selected from Table 2 (groups 55 to 95);
R2 is H or Ac;
R5 is H or Me or Ac or Ph or Bz or G1 or G2 or G3 or G4 or G5 or G6 or G7 or G8 or G9 G10 or G11 or G12 or G13;
R6 is H, only in the case when R5 is G10 the group R6 is H or Me;
General Method
In accordance with this invention, halogenated cephalomannine, paclitaxel or other taxane analogs can be prepared in good yields from relatively refined sources of cephalomannine, paclitaxel and other taxane compounds. The analogs are prepared by selective halogenation of the different aliphatic or aromatic saturated or unsaturated acids, further converted to acyl halogenides or halogenated aliphatic or aromatic unsaturated alchohols or phenols, converted with phosgene to the corresponding formates, while leaving portions or moieties of the molecule or other important taxane compounds in the mixture, such as 10-deacetyl-baccatin III, Baccatine III, Cephalomannine, Taxotere, Paclitaxel, undisturbed and unreacted.
Separation and purification of halogenated analogs which show strong antitumor efficacy from the mixture can be accomplished by conventional or other modem methods.
Halogenation of unsaturated or saturated aliphatic or aromatic acids can be done by some classical reactions bubolling the halogene through the cold solution of the above mention compounds or by addition dropwise or pure halogene or disolved in nonpolar solvents as methylene chloride, ethylene dichloride, chloroform, carbon tetrachloride, following by separation and purification of the resulting less polar mixture to individual pure compounds using classical or modem methods (destilation, crystalization, chromatography etc.).
Halogenation of unsaturated or saturated alcohols or phenols can be done using the methods so close to these used for production of halogenated aliphatic or aromatic acids.
The synthetic methods of this invention are advantageously independent of the concentration of starting compunds with taxan structure present in various bulk products as 10-deacetyl-baccatin III, Baccatin III, debenzoyleted cephalomannine and Paclitaxel or Cephalomannine Taxotere and Paclitaxel.
All of them can be obtained from natural sources, or by synthetic or semisynthetic methods.
The reaction between mono-or dichalogenated acyl halogenides, can be done in solution of nonpolar solvents as dichloromethane, dichloroethane, chloroform, carbontetrachloride at room (or lower) temperature in presents of some organic or inorganic reagents as N,N,N,-triethylamine, pyridine etc., to catch the HX coming from the reaction.
On the same way are provided and the reactions between halogenated alcyl (or aryl-)-oxy-carbonyl-halogenides with amino acids or taxane derivatives.
There are different ways for preparation of formates: 1. Preparation of formates from halogenated alchohols or phenols by reaction with phosgene, followed by purification or the product. Next step is the reaction of the formate with amino acids or taxane derivatives.
In the last reaction can be used ready made formates. 2. Combined (one step) reaction between halogenated derivatives (alcohols or phenols), phosgene and amino acids or taxane compounds.
All reactions of this invention are shown on the following schematic diagram (Reactions I to VII). 
The resulting pure halogenated compounds can be separated and their chemical structures elucidated by conventional, analytical and physicochemical techniques.
The reaction mixture containing taxane impurities can then be separated and purified by conventional methods such as chromatography and recrystallization and the individual separated and halogenated analogs made available for antitumor treatment.
Halogenated paclitaxel analogs of the general structure Type I of this invention can be prepared by the following synthetic route: 
where R1 is a dihalogenated or halogenated acyl group selected from Table 1, groups 1-40, and R2 is H or Ac.